The present invention relates to caissons used in construction and, more particularly, to caissons having steel cores.
Relatively light buildings can be constructed on packed dirt or stone. In fact, certain structures, such as single-level houses, can be constructed without foundations. Heavier buildings, however, require concrete or steel reinforced concrete foundations and/or footers, preferably disposed on bedrock.
In certain situations, however, the site or portions of a site for a large, heavy building lacks such bedrock. Accordingly, for those situations, holes are often drilled into the ground and concrete caissons are inserted. The caissons form a support structure for the foundation or footers.
Again, for lighter buildings, conventional concrete caissons are adequate to support the building load. However, as the weight of the building increases, the concrete caissons must either increase in diameter or the number of caissons must increase. At a certain point, the size of the caissons becomes unmanageably large. Reinforcing steel or xe2x80x9crebarsxe2x80x9d have been used to reinforce the concrete. A conventional, reinforced, 24xe2x80x3 diameter caisson is rated at 1,300 tons. However, once again, there is a limit to the support strength of even reinforced concrete caissons. Concrete caissons that are reinforced with heavier steel in the form of I-beams and H-beams result in stronger support, but are still inadequate in certain situations.
U.S. Pat. No. 6,197,395, issued to Van Vechten et al on Mar. 6, 2001 for HOLLOW REINFORCING MEMBERS AND COMPOSITES CONTAINING THE SAME, discloses a hollow reinforcing element for casting into composites. Passageways are defined for communicating to the exterior of the composite. These passageways served as conduit arrays in structures formed from the composite. The structure is not used to support a load.
U.S. Pat. No. 4,627,212, issued to Yee on Dec. 9, 1986 for SPLICE SLEEVE FOR REINFORCING BARS WITH CYLINDRICAL SHELL, discloses a splice sleeve for receiving and connecting adjoining ends of a pair of reinforcing bars or rods. The sleeve has an internal surface with ridges that provide a wedging action and compression of grouting introduced into the shell.
U.S. Pat. No. 3,955,600, issued to Tamburello on May 11, 1976 for COMPOSITE PIPELING, discloses a composite pipeline for use in deep water. Once again, the pipeline is hollow and includes a concrete coating integrally bonded to the pipeline. The structure is used as a conduit, rather than a support structure.
U.S. Pat. No. 3,552,787, issued to Yee on Jan. 5, 1971 for WIRE CAGE-TYPE SPLICE SLEEVE FOR REINFORCING BARS, discloses a wire cage splice sleeve for reinforcing bars.
It would be advantageous to provide a concrete caisson with a steel core.
It would also be advantageous to provide a steel core caisson that has greater strength than that provided in conventional reinforced steel core caissons.
In accordance with the present invention, there is provided a caisson for use as a support structure in building construction. The caisson has a cylindrical, inner, metallic core and a cylindrical outer portion surrounding the inner core, in the preferred embodiment. Metallic bands can be disposed peripherally, in spaced apart relation, around the inner core for anchoring it to the outer portion of the caisson. The inner core of the caisson is at least 29%, and preferably more than 34% of the total cross sectional area of the caisson. The inner, metallic core is usually steel and the outer portion is concrete. A caisson manufactured in accordance with the invention is capable of supporting more than 2,400 tons (22xe2x80x3 O.D.) or more than 2,700 tons (24xe2x80x3 O.D.). A hollow, cylindrical, steel shell optionally surrounds the outer periphery of the outer portion of the caisson.